This invention relates generally to building structures made of concrete, and more particularly to those cast on the building site and assembled by tilting the walls into a vertical position.
Prior art buildings of the "tilt-up" type have required long periods of curing of the concrete, in order to develop sufficient strength to be moved around into position and connected into place. In the past, this type of construction has been used mostly for single story industrial buildings, since they do not require a second floor. A wooden roof with beams can then provide the structure tying together the tops of the walls.
As higher tilt-up wall panels are poured, thicknesses must increase to allow sufficient strength for them to be hoisted into position. Larger floor areas must also be available for the initial pouring in a horizontal position. Hoists of greater capacity are required to lift them, and the whole operation becomes much more expensive.
There have been several attempts to provide horizontally cast ceiling panels that can then be hoisted into position. One such system is found in U.S. Pat. No. 1,066,436 issued July 1, 1913 to Pelzer. In this case, columns are formed, then used to raise the ceiling panels. In U.S. Pat. No. 4,030,257 issued June 21, 1977 to Labie et al., a floor slab is disclosed that can be poured in nested fashion, with reinforcing beams added to each floor when on top of the stack, providing bending strength while being lifted into final position. The floors are then bolted to the vertical supporting walls. Watry, in U.S. Pat. No. 4,147,009 issued Apr. 3, 1979 casts floor panels in small sections and assembles them in place with tension cables and mortar.
It is a well-recognized need that the present invention addresses, particularly in the low-cost housing area. A primary object of this invention is therefore to provide a rapid and simplified system for constructing housing units.
Another object is to allow high quality inexpensive housing to be constructed without the use of expensive construction equipment.
An additional object is to develop a construction system that takes advantage of the rapid-curing and light weight and thermal insulating characteristics of accelerated low-slump concrete.
A further object of the invention is the elimination of the necessity for mechanical connections between concrete elements.
Another object is the provision of a simple system for elevating floor slabs, and for tying them into the wall structures.
A still further object of the invention is to disclose a structural unit that can be repeated to form multi-story and multiple-room buildings, eliminating the need for large wall panels.